Hurricane Wilma was the most intense hurricane that has ever been recorded in the Atlantic basin. It devastated parts of the Yucatán Peninsula and southern Florida during October in the 2005 Atlantic hurricane season. Wilma set numerous records for both strength and seasonal activity. Wilma was only the third Category 5 ever to develop in the month of October and with the formation of Hurricane Wilma, the 2005 season became the most active on record, exceeding the 21 storms of the 1933 season. Wilma was the twenty-second storm (including the subtropical storm discovered in reanalysis), thirteenth hurricane, sixth major hurricane, and fourth Category 5 hurricane of the record-breaking season.

Wilma made several landfalls, with the most destructive effects felt in the Yucatán Peninsula of Mexico, Cuba, and the U.S. state of Florida. At least 63 deaths were reported, and damage is estimated at over $28.9 billion ($20.6 billion in the US; 2005 US dollars),[1] ranking Wilma among the top 5 costliest hurricanes ever recorded in the Atlantic and the third costliest storm in U.S. history.

Figure 1: The track of Hurricane Wilma with images of the Cyclone at specific times
Image Credit: NOAA

The origin of Hurricane Wilma is complicated. During the second week of October, an unusually large, monsoon-like lower-level circulation and a broad area of disturbed weather developed over much of the Caribbean Sea. The system was enhanced by diffluence—the rate at which a fluid moves—from an upper-level low across the southwestern Atlantic. By October 13, a broad area of low pressure developed and persisted about 150 miles (240 km) southeast of Jamaica, possibly aided by the passage of tropical waves through the area at the time. Convection increased and became slightly better organized, though upper-level wind shear initially prevented development. The system drifted westward, and early on October 14 the convection became more concentrated and a little better organized as upper-level wind shear lessened slightly.

Later on October 14, the system became much better defined, with increasingly organized shower and thunderstorm activity, as conditions in the upper levels of the atmosphere became significantly more favorable. It was then that the National Hurricane Center first indicated that it was possible for a tropical depression to develop in the area. Dvorak classifications were initiated on October 15. The system continued to organize, with the National Hurricane Center remarking the system could ultimately become a hurricane.[5] By late on October 15, the surface circulation became defined well-enough, with sufficiently organized deep convection, for the National Hurricane Center to designate the system as Tropical Depression Twenty-Four while it was located about 220 miles (345 km) east-southeast of Grand Cayman.

The depression tracked slowly westward, a motion due to weak steering currents caused by a high pressure system to its north across the Gulf of Mexico. Initially, the center of circulation was broad without a defined inner core; forecaster Lixion Avila remarked, "The area of minimum pressure could [have been] anywhere within 60 miles (95 km) of its [initial advisory position]." Initially, the tropical depression was forecast to drift west-southwestward before turning to the north; within 120 hours of the forecast's issuance, the system was predicted to be located about 80 miles (130 km) south of the Isle of Youth as a hurricane with winds of 91 knots (105 mph) . However, the National Hurricane Center noted in the first advisory on the depression that there were "all indications that there could a dangerous hurricane in the northwestern Caribbean Sea in 3 to 5 days." This was due to the depression being located within an environment very conducive for development, specifically low amounts of wind shear and very warm water temperatures.

As Tropical Depression Twenty-Four drifted southwestward, it steadily organized; by early on October 16, rainbands began to gradually consolidate with well-established outflow, and a large upper-level anticyclone developed over the depression. Although deep convection and banding features increased, mid-level dry air from the north prevented significant organization, and the convection was split into two primary areas. Surface buoy reports indicated that, due to its large size, the system failed to strengthen beyond tropical depression status, even though it received tropical storm strength Dvorak classifications from The National Hurricane Center's Tropical Analysis and Forecast Branch and the National Oceanic and Atmospheric Administration's Satellite Analysis Branch. Continued reconnaissance flights reported peak winds of about 26 knots (30 mph)

By early on October 17, the outer rainbands, which had previously dominated the structure of the cyclone, dissipated, while deep convection developed near and to the south of the center. Computer models predicted steady strengthening as the depression tracked westward before turning to the north. Of the intensity models, the Geophysical Fluid Dynamics Laboratory predicted an intensity of 117 knots (135 mph) within 36 hours, with other forecasts being more conservative in their predictions. Deep convection continued to develop to the south of the center, and the depression intensified into Tropical Storm Wilma at 0600 UTC on October 17, while located about 200 miles (320 km) southeast of Grand Cayman. Upon becoming a tropical storm, the National Hurricane Center predicted Wilma to track west-northwestward, reaching winds of 91 knots (105 mph) before striking the northeastern portion of the Yucatán Peninsula. The storm continued to the southwest while deep convection persisted near the center. National Hurricane Centner forecaster James Franklin remarked, "Confidence at the later ranges [of the forecast track] was unusually low", due to wide divergences between computer models. Late on October 17, a Hurricane Hunters flight into Wilma recorded winds of 50 mph (80 km/h), but an unusually low pressure of 989 hPa, which would be more typical of a minimal hurricane. This was due to unusually low pressures across the region, which resulted in a lesser pressure gradient and thus lighter winds. Convection continued to develop near the center and became much more symmetrical.

It continued to intensify, and at 1200 UTC on October 18, Wilma attained hurricane status while located about 225 miles (360 km) south-southeast of Grand Cayman. Shortly after reaching hurricane strength, the hurricane began undergoing explosive deepening, subsequent to the development of a "pinhole" eye 9 miles (14 km) in diameter. This small eye was surrounded by a ring of deep convection, with cloud-top temperatures of about -125 °F (-87 °C).

Early on October 19, Wilma attained major hurricane status while continuing to rapidly intensify, and by 0600 UTC, the storm's maximum sustained winds increased to 147 knots (170 mph), making Wilma a dangerous Category 5 storm on the Saffir-Simpson Hurricane Scale. In the span of just 24 hours, Wilma had intensified from a 60 knot (70 mph) tropical storm to a 152 knot (175 mph) Category 5 hurricane, an unprecedented event for an Atlantic hurricane. The eye continued to contract to a diameter of about 3 miles (5 km), the smallest known eye in an Atlantic hurricane, and at 1200 UTC on October 19, Wilma attained peak winds of 160 knots (185 mph). The central pressure rapidly dropped 54 hPa from 0000 to 0600 UTC, and at 0800 UTC, a Hurricane Hunters flight recorded a minimum central pressure of 884 hPa n a dropsonde near the center of the extremely small eye. As the dropsonde did not reach the calm winds in the center, the pressure was estimated at 882 hPa, the lowest pressure in an Atlantic hurricane on record. The pressure continued to fall as the Hurricane Hunters left the hurricane, and it is possible the pressure was slightly lower. Operationally, the peak intensity was estimated at (175 mph). At the time of its peak intensity, hurricane force winds extended only 50 miles (85 km) from the small center of Wilma, with tropical storm force winds extending only about 160 miles (260 km).

Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled

Rating:
Topic views: 3619

Rate this topic

Jump to

Note: This is NOT an official page. It is run by weather hobbyists and should not be used as a replacement for official sources.
CFHC's main servers are currently located at Hostdime.com in Orlando, FL.
Image Server Network thanks to Mike Potts and Amazon Web Services. If you have static file hosting space that allows dns aliasing contact us to help out! Some Maps Provided by:
Great thanks to all who donated and everyone who uses the site as well.
Site designed for 800x600+ resolution
When in doubt, take the word of the National Hurricane Center